Carburetor



Aug. 27, 1940.

F. C. MOCK ET AL CARBURETOR Filed May l0, 193'?I 2 Sheets-Sheet l m ,M vC.. .W w F Vw u EM/z. O. M//Q INVEIE/RS.

e 5% @Wg ATTORNEY Aug. 27, 1940. F. c. MocK ET Al.

CARBURETOR Filed May l0, 1937 2 Sheets-Sheet 2 Fen/9K C. Mock DWL O. tlv/@TH INVENTOR.

Yea ATTORNEY.

Patented Aug. 27, 1940 CABBURETOR Frank C. Mock and Emil O. Wirth, South Bend, Ind., assigner: to Bendix Products Corporation, South Bend, Ind., a corporation of Indiana Application May 10, 1937, Serial No. 141,820

16 Claims. (Cl. 26141) vide a carburetor in which the fuel supply is in.

creased during acceleration to provide a richer mixture, the increased fuel supply being maintained over an appreciable period of time so that the engine can accelerate properly.

Another object of the invention is to provide acaburetor in which the richness of the mixture is increased during operation under heavy load or at high speed.

Other objects,I advantages and novel features of the invention will be apparent from the following description when read in connection with the accompanying drawings. in which:

Figure 1 is a central section with parts in elevation of a carburetor embodying the invention;

Figure 2 is an enlarged partial view of the carburetor of Figure 1: and

Figures 3 to 6 are views similar to Figure 2 showing various modified constructions.

Referring more particularly to Figures 1 and 2, there is shown a carburetor including a downdraft conduit I constricted at I2 to form a venturi and connected at its lower end to an engine manifold I4. The carburetor is provided with the' usual choke and throttle valves I6 and I8 and has a fuel chamber 20 formed around the conduit I0 receiving fuel fr`om a passage 22 leading to any suitable source under the control of a float operated valve 24. Fuel from the chainber 20 is supplied to a stream of air flowing through the conduit I0 by a main nozzle 26 opening at its lower end through a metering orice into the lower part of the fuel chamber and discharging into an auxiliary venturi 28 which is mounted in the conduit I0 substantially at the throat of the main venturi I2. Y

In order to provide a temporary increase in the supply 'of fuel as the throttle is opened, there is provided a pump cylinder 30 communicating at its upper end with the top of the fuel chamber and having an inlet 32 provided with a check valve connecting its lower end to the lower part of the fuel chamber. A piston 34 is slidably mounted in the cylinder 30 and is formed with a central'vent closed by a float valve 36. If any vapor collects in the pump cylinder the valve 36 will open to permit its escape through the vent in the piston but as the liquid rises the valve 364 will float to closed position to prevent its escape.

'I'he piston 34 is connected, by a lost motion connection indicated at 31, to a rod 38 operated by 'an arm 40 which is connected through suitable linkage, not shown, to the throttle valve It so that when the throttle is opened the rod will be moved down. A spring 42 urges the piston 34 down and tends to maintain a continuing pump discharge within the limits of the lost motion connection as the throttle is opened.

Fuel from the cylinder 30 discharges past a tapered valve 44 into an annular chamber 46 which communicates with a chamber 48 closed on one side by a flexible diaphragm 50. The valve .44 is connected directly to the diaphragm 50 which is connected on its other side to the conduit IIl posterior to the throttle by a pipe 52 to be responsive to the suction therein. A spring 54 in the chamber 46 urges the valve 44 off its seat in opposition to the suction on the diaphragm 50 and the valve 44 is formed with a by-pass controlled by a check valve 56 to permit discharge of fuel from the pump cylinder celeration. The amount of fuel supplied is proportional to the amount of throttle opening and is continued as long as opening movement of the throttle continues. A difficulty with acceleration pumps of known types has been that at low engine speeds with small throttle opening, a relatively small amount of throttle movement will provide a full air charge to the engine but will not operate the pump sufficiently to provide a full fuel charge. With the present device, however,lunder conditions just mentioned, suction jon the diaphragm 5I) decreases allowing the diaphragm to move up under the influence of spring 46 to force fuel from the chamber 48 through the nozzle 58 to provide a full fuel charge. Suction on thediaphragm 50 will also drop if a load isA applied to the engine without moving ythe throttle and under these conditions the diphragm will also operate as ayvacuum controlled fuel pump to increase the fuel charge. Thus the combination of the throttle operated pump and vacuum pump provides an accelerating charge of fuel under all conditions when it is desired.

The valve 44 controlled by the diaphragm 50 also serves to increase the fuel charge when there is a full air charge (low suction) by slightly raising valve 44 from-its seat to open a passage from the fuel chamber to the nozzle 5B. Thus when the engine is working under heavy load or at -or near wide open throttle the valve 44 will open and fuel will flow from the fuel chamber chamber 46 and passage 55 into the nozzle 58 to increase the fuel charge. to the engine.

Flgurel 3 illustrates a slight modification of the structure of Figure 1 in which the piston 34 is replaced by a diaphragm 35. Otherwise the structure and operation are the same and parts corresponding to like parts in Figure 1 have been indicated by the same reference numerals.

Figure 4 shows another carburetor embodying the invention, parts therein corresponding to like parts in Figures 1 and 2 being indicated by the same reference numerals plus |00. In this form the diaphragm 50 is replaced by a vacuum actuated piston |50 connected to a plunger |5| by a rod |53. 'I'he spring |54 urges these pistons downwardly and a suction connection |52 transmits suction from a point posterior to the throttle valve to the top of the piston |50 to tend to raise it. The valve 44 has been replaced by a spring closedeconomizer valve |44 controlling communication from the space |55 below the plunger |5| to the space |46 which communicates through a passage |41 with the main nozzle |26 above the metering orice therein. The valve |44 has an elongated stem projecting upwardly to be engaged by the plunger |5| when it moves down thereby to open the valve and increase the supply of fuel to the main nozzle.

A passage I 3| connects the pump cylinder to -the space below plunger |5| and a passage controlled by a check valve |51 connects it to the auxiliary fuel nozzle |58. Preferably the spring holding the valve |51 closed is weaker than that closing the valve |44 so that under normal pumping operation the fuel from the pump will ow through valve |51 and out the auxiliary nozzle |58.

In order that the economizer valve |44 may be operated in accordance with throttle position as Well as by variations in suction, the piston |34 carries a bracket 62 having a split end straddling the piston rod |53. Thus when the throttle is opened substantially fully, as for high speed operation, thev bracket will force plunger |5| downwardly so that valve |44 will be opened to increase the supply of fuel to the main nozzle. With this construction it is desirable to proportion the piston |50 and spring |54 so that the piston will not move down until the suction falls to approximately two inches of mercury or less so that the plunger |5| will not open valve |44 during small throttle openings as in driving an automobile in trame. This increases the economy and at the same time provides an increased fuel supply at high speed when the suction is greater than two inches of mercury because the throttle under such circumstances is substantially fully open and bracket |62 is bearing down on piston |5|.

With a vacuum pump of usual design, each time the engine is stopped the vacuum is broken and the pump discharges, which is not desirable. Also at extremely low speed with the throttle nearly closed it is desired to keep the economizer valve closed regardless of the suction since a rich mixture is provided at this time by the usual idling mechanism. In the carburetor of Figure 4 the vacuum pump is kept from discharging and the economizer valve is retained closed during closed throttle operation by providing a pin |64 on the piston rod |53 above the end of the bracket |62. When the throttle is closed as when the engine is stopped the pin |64 engages the bracket |62 to prevent the pistons |50 and |5| from moving dawn to any appreciable extent so that no fuel can' be pumped thereby. When the throttle is opened only slightly for slow speed operation the plunger |5| may move down to some extent but not enough to open the economizer valve |44. However, in the normal operating range the bracket |62 does not materially restrict movement of the plunger |5| which is then free to move an amount equal to the disbtance between itself and the pin |64.

Figure 5 illustrates another embodiment of the invention, parts therein corresponding to like parts in Figure 4 being indicated by the same reference numerals plus 100. In this embodiment the economizer valve 244 is placed in the lower part of the pump cylinder 230 with its end projecting into that cylinder to be engaged by the piston 234. The economizer valve also serves as a pump outlet check valve and the discharge from both the mechanical pump 234 and the vacuum' pump 25| is conducted past it and through the nozzle 258. The operation of this embodiment is similar to that of Figures 1 and 2 except that the economizer valve is operated by the throttle and it represents a simplification of the form shown in Figure 4 with omission of certain of the functions.

Figure 6 illustrates still another embodiment of the invention, parts therein corresponding to like parts in Figures 1 and 2 being indicated by the same reference numerals plus 300. In this construction a housing part 366 formed with a cylindrical extension is secured to the fuel chamber clamping the diaphragm 350 between them. 'I'he diaphragm is not connected to the economizer valve 344 but is adapted to engage a stem thereon to open the valve.

A sleeve 368 is slidably mounted in the part 366 and has a lost motion connection with a rod 310 which is connected to the diaphragm 350, a spring 312 urging the rod and diaphragm to the limit of their travel in the downward direction away from the valve 344. The sleeve 368 carries a second rod 314 which is connected through a lost motion connection to a yoke member 316, a spring 318 urging the yoke member away from the sleeve. The yoke member is connected to one arm of a bell crank lever 380, the other arm of which is connected through a link 382 to a lever 384 which is carried by the throttle valve shaft.

The valve 344 controls ow of fuel through a passage 341 into the main nozzle above the metering orifice. 'Ihe auxiliary nozzle 358 communicates with the chamber 348 past a check valve 351 which is urged onto its seat by a spring weaker than the spring urging the valve 344 closed so that in normal pumping operation fuel will be discharged past the valve 351 through the auxiliary nozzle. However, when the diaphragm moves far enough it will engage and open the valve 344 to increase the supply of fuel to the main nozzle.

In operation, the diaphragm 350 is responsive y to variations in suction within the limits permitted by the lost motion connection between sleeve 368 and rod 310 and also to movements of the throttle. The lost motion connection is so arranged that when the throttle is closed substantially no movement of the diaphragm is permitted, when the throttle is only slightly open the diaphragm can move but not enough to open valve 344 and when the throttle is in the normal operating range the diaphragm is substantially free to move in response to variations in suction in much the same manner as described in connection with Figure 4. When the throttle is opened wide it moves the sleeve 368 suiciently to open th valve 3 so that this valve is controlled at parti throttle openings by suction and at wide open throttle by throttle position and suction.

While several embodiments of the invention have been shown and described, it will be apparent that many changes might be made therein and it is not intended to limit the scope of the invention to the illustrated embodiments nor otherwise than by the terms of the appended claims.

What is claimed is:

l. A carburetor comprising a mixture conduit, a throttle valve` in said conduit, a fuel reservoir, a pump chamber connected to said fuel reservoir, a fuel displacement member forming a closure for said pump chamber and connected to the throttle valve to be operated thereby, said member formed with a by-pass opening, valve means including a oat in said opening and adapted to open by gravity when insumcient fuel v is in contact therewith to permit escape of vapor but to close the opening against the-passage of liquid fuel thereby to maintain.the pump chamber full of liquid fuel, and a nozzle connected to the pump chamber and discharging into the mixture conduit.

2. A carburetor comprising va. mixture conduit, a throttle valve in said conduit, a fuel chamber, a pump chamber connected to said'fuel chamber and having the pumping portion thereof positioned below the normal level of the fuel in said fuel chamber, a fuel displacement member forming a closure for the top of the pumping portion of the pump chamber and connected to the throttle valve to be operated thereby, said member formed with a by-pass opening, valve means including a float in saidopening to open the opening and permit escape of vapor but to close the opening against the passage of liquid fuel thereby to maintain the pumping portion of the pump chamber full of liquid fuel, a second pump chamber having aMmovable member, a passageway interconnectig said pump chambers whereby said last movable member is subjected to pressures created in the first mentioned -pump chamber, a nozzle connected to one of 'said chambers and discharging into'the mixture conduit, and a pressure responsive member subjected to the pressure in the mixture conduit posterior to the throttle valve and connected to said second named movable member.

3. A carburetor comprising a mixture conduit having a throttle valve therein, fuel v supply means, a pair of interconnected pump chambers communicating with said fuel supply means, plunger members for discharging fuel from said chambers, throttle operable means for actuating one of said plungers, means subjected to the suction in the mixture conduit posterior to the -throttle and attached to the other plunger whereby said second named plunger is actuated conjointly by variations in said suction and byV variations in the fuel pressure in said chambers, resilient means acting on said last means in opposition to said suction, and a nozzle communicating with said chambers and discharging into the mixture conduit.

4. A carburetor comprising a mixture conduit, a throttle valve therein, fuel supply means, a pair of interconnected pump chambers communicating with said fuel supply means,plunger members for discharging fuel from said chambers. throttle operable means for actuating one of said plungers, resilient means for urging the other plunger into its chamber, means subjected to the suction in the mixture conduit posterior to said throttle for urging said other plunger out of its chamber, and a nozzle communicating with saidl connected to the other plunger thereby to make the other plunger responsive both to the suction in the mixture conduit and the fuel pressure in said chambers, means including a nozzle connected to one of said chambers and discharging into the mixture conduit, and a normally closed check valve in said last named means, said check valve adapted to open when the pressure in said chambers exceedsa predetermined value.

6. A carburetor comprising a mixture conduit having a throttle valve, fuel supply means, a pair of interconnected pump chambers communicating with said fuel supply means, plunger members for displacing fuel from said chambers, manually operable means for actuating one of said plungers, means subjected to the suction in the mixture conduit posterior to said throttle and attached to the other plunger to cause said other plunger to move responsive both to the suction in the mixture passage and the fuel pressure in said chambers, means including a nozzle connected to the chamber containing said other'plunger and discharging into the mixture conduit, and a valve in said last named means, said valve including a part projecting into' the last named chamber to be engaged by said other plunger` charging fuel from said pump into the mixing conduit, a supplemental fuel conduit for conducting an auxiliary supply of fuel to the main nozzle posterior to said restriction, a normally closed economizer valve in said conduit, and means subjected jointly to variations in the pressure in the mixing conduit posterior to the throttle and to variations in the fuel pressures produced by actuation of the pump for opening said economizer valve.

8. The invention defined in claim 7 including means operated by the accelerating pump and operative at or near wide open throttle to open the economizer valve regardless of the degree of suction in the mixing conduit.

9. A carburetor comprising an induction passage, a throttle valve therein, a fuel reservoir, a main nozzle having a metering restriction therein and connecting the reservoir and mixing conduit, an accelerating pump connected to the throttle to be actuated by throttle opening movement, a supplemental fuel conduit connecting the reservoir to the main nozzle posterior to said restriction, single means subjected to pressures in the induction passage posterior to the throttle and to fuel pressure produced by operation of the pump for? controlling flow through said supplemental fuel conduit, and a mechanical connection between the throttle and said means for positively opening the supplemental fuel .conduit whenever the throttle is at or near its wide open position.

10. A carburetor comprising a mixture conduit having a throttle valve therein, a fuel supply source, a main nozzle conducting fuel from said source into the conduit including a metering restriction, an accelerating pump connected to the throttle to be operated thereby, an auxiliary fuel passage to conduct fuel from said pump into the conduit, a normally closed economizer valve controlling said passage, and means subjected both to variations in the pressures in the mixture conduit-posterior to the throttle valve and to variations in the fuel pressures "created by actuation of the pump for opening said economizer valve.

l1. In a carburetor having an induction passage anda throttle valve therein, a pump chamber having a pumping member actuated by throttle movement, a second pump chamber connected to said first pump chamber by a pressure equalizing passage, a second pumping member in said second pump chamber yieldingly positioned to respond to both variations in the pressure in the induction passage posterior to the throttle valve and to variations in the fuel pressure in said chambers, a valve controlled outlet from one of said pump chambers controlled by the pressure of fuel in said chambers, and a second valve controlled outlet from one of said pump chambers controlled by the position of one of said pumping members.

12. A carburetor having a mixture passage, a throttle valve therein, a fuel chamber, a main nozzle for supplying fluid from said chamber to said passage, said nozzle having a metering restriction therein, a throttle operated accelerating pump having a chamber communicating with the fuel chamber and having a valve controlled outlet conduit discharging into the passage, a suction operated pump including a chamber communicating with the fuel chamber and with the first named pump chamber and with the nozzle posterior to said restriction, said suction operated pump including means subjected to suction in said passage posterior to the throttle, and resilient means associated with said last named means and tending to cause a discharging operation of said suction operated pump in opposition to the effect of said suction and the pressure of the fuel created in said first pump chamber by operation of said accelerating pump.

13. A carburetor having a mixture passage, a throttle valve therein, a fuel chamber, a main nozzle for supplying iiuid from said chamber to said passage, said nozzle having a metering restriction therein, a throttle operated accelerating pump having a chamber communicating with the fuel chamber and having a valve controlled outlet conduit discharging into the passage, a suction operated pump including a chamber communicating with the fuel chamber and with the first named pump chamber, a conduit connecting said last chamber with the nozzle posterior to said restriction, a valve in said last named conduit, said suction operated pump including means subjected to suction in said passage posterior to the throttle, and resilient means associated with said last means and tending to cause a discharging operation of the suction operated pump in suction operated pump when the latter attains' its discharged position under the action of said resilient means.

14. A carburetor having a mixture passage, a throttle valve therein, a fuel chamber, a main nozzle for supplying fluid from said chamber to said passage, said nozzle having a metering restriction therein, a throttle operated acceleratingr pump having a chamber communicating with the fuel chamber and having a valve controlled outlet conduit discharging into the passage, a suction operated pump including a chamber communicating with the fuel chamber and with the first named pump chamber, a conduit connecting said last chamber with the nozzle posterior to said restriction, a valve in said last named conduit, said suction operated pump including means subjected to suction in said passage posterior to the throttle, resilient means associated with said last means and tending to cause a discharging operation of the suction operated pump in opposition to the effect of said suction and the pressure of the fuel created in said flrst pump chamber by operation of said accelerating pump, said second named valve being opened by said suction operated pump when the latter attains its discharged position under the action of said resilient means, a pair of sp'aced abutments carried by said suction operated pump, and means carried by said accelerating pump and arranged to engage said abutments whereby the suction operated pump is prevented from moving to discharge position when the throttle is in normal closed position and is moved to discharge position when the throttle is fully opened.

15. A carburetor comprising an induction conduit, a throttle valve in said conduit, a fuel reservoir, a fuel duct interconnecting the reservoir and conduit and having a metering restriction therein, and an acceleration pump comprising a fuel chamber having fixed and two spaced movable walls, throttle operated mechanism to move one of said walls inwardly when the throttle is opened, means communicating with the induction conduit posterior to the throttle for withdrawing the other of said walls when suction in the conduit increases, a spring urging said 'other wall inwardly in opposition to the suction,

- a passageway from the reservoir to the chamber and a restricted passageway from the chamber to the induction conduit.

16. A carburetor comprising a mixture conduit, a throttle valve in said conduit, a fuel reservoir, two parallel vertically extending acceleration pump wells, depending fuel displacement members in said wells, passages intercommunicating the lower portions of said wells with each other and with the fuel reservoir and the mixture conduit, the passage to the mixture conduit being restricted, a throttle operated device for actuating one of said members, and a suction operated element subjected to the suction in the mixture conduit posterior to the throttle and including resilient means opposing the suction for actuating the other of said members.

FRANK C. MOCK. EMIL O. WIR'I'H. 

